二维共边四面体磁体FeX（X=Te, Se）中键依赖类Kitaev相互作用的建模
Modeling Bond-Dependent Kitaev-like interaction in 2D Edge-Sharing Tetrahedral Magnets: FeX (X=Te, Se)
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中文总结 AI 辅助
该研究构建FeTe和FeSe的类Kitaev模型，揭示共边四面体磁体存在键依赖伊辛型相互作用，确立其为键依赖相互作用新载体，扩展Kitaev物理范围。
中文摘要 AI 辅助
以Kitaev模型为代表的键依赖磁相互作用源于自旋轨道耦合（SOC）与特定配位几何的相互作用，目前这类相互作用主要发现于共边八面体体系，而与铁基超导体母体化合物相关的共边四面体环境中是否存在类似相互作用仍是开放问题。本文构建了单层FeTe和FeSe的类Kitaev模型，证明存在由硫族元素介导的SOC与四面体晶体场几何共同诱导的、此前未被认识的键依赖伊辛型相互作用。通过对代表性线性磁序的磁各向异性能量映射进行第一性原理计算，我们将键依赖贡献与单离子各向异性区分开，发现类Kitaev相互作用主导FeTe的磁各向异性，而在FeSe中，它与符号相反的单离子各向异性剧烈竞争；产生的非共线局域各向异性轴形成本征单格点自旋阻挫，为超出各向同性交换模型的磁无序提供了微观机制。我们的结果确立共边四面体磁体是键依赖相互作用的新载体，将Kitaev物理的范围扩展到八面体配位之外。
英文摘要
Bond-dependent magnetic interactions, exemplified by the Kitaev model, are known to arise from the interplay between spin-orbit coupling (SOC) and specific coordination geometries, but have so far been almost exclusively identified in edge-sharing octahedral systems. Whether such interactions persist in edge-sharing tetrahedral environments, characteristic of the parent compounds of iron-based superconductors, remains an open question. Here, we construct a Kitaev-like model for monolayer FeTe and FeSe and demonstrate the presence of a previously unrecognized bond-dependent Ising-type interaction, induced jointly by chalcogen-mediated SOC and the tetrahedral crystal-field geometry. A microscopic spin model for these bond-dependent interactions is derived via strong-coupling perturbation theory, and the strengths of the individual exchange terms are extracted by partitioning the magnetic anisotropy energy calculated using density functional theory across various collinear magnetic orders. We reveal that the Kitaev-like interaction dominates the magnetic anisotropy in FeTe, whereas in FeSe, it strongly competes with a single-ion anisotropy of opposite sign. The resulting noncollinear local anisotropy axes generate intrinsic single-site spin frustration, providing a microscopic mechanism for magnetic disorder that transcends isotropic exchange models. Our results establish edge-sharing tetrahedral magnets as a new platform for bond-dependent interactions and extend the scope of Kitaev physics beyond octahedral coordination.
